The role of bone marrow microenvironment (BMM) cells in acute myeloid leukemia (AML) progression: immune checkpoints, metabolic checkpoints, and signaling pathways

Causal relationship between 731 immune cells and the risk of myeloproliferative neoplasms: A 2-sample bidirectional Mendelian randomization study

Myeloproliferative neoplasms (MPN) are chronic hematological disorders marked by the abnormal proliferation of bone marrow cells. The most commonly encountered forms are polycythemia vera (PV), primary myelofibrosis (PMF), and essential thrombocythemia (ET). These disorders are generally associated with increases in blood components, which can lead to conditions like splenomegaly, thrombosis, bleeding tendencies, and a heightened risk of progressing to acute leukemia. Previous research has indicated a possible link between immune cells and MPN, yet this association is still poorly understood. This study seeks to elucidate the causal relationship between immune cell characteristics and the development of MPN. In this study, we employed Mendelian randomization (MR) to investigate potential causal links between 731 immune cell traits and the risk of developing MPN, leveraging data from genome-wide association studies (GWAS). To ensure the robustness of our findings, we conducted extensive sensitivity analyses to assess heterogeneity and detect any pleiotropic effects. Moreover, we implemented a false discovery rate (FDR) correction to mitigate the risk of false positives that may result from the multiple hypothesis testing, thereby adjusting for any statistical biases due to multiple comparisons. The immune phenotype IgD on IgD+ CD24- B cells demonstrated a statistically significant protective effect against MPN (PFDR = 0.047). Upon adjusting the significance threshold to PFDR < 0.20, 16 immune cell phenotypes were significantly associated with MPN. Among these, 11 were found to exert a protective effect against MPN, 5 phenotypes were associated with an elevated risk of MPN. This research highlights a significant association between various immune cell phenotypes and the risk of developing MPN, thereby advancing our understanding of the intricate interplay between immune cell traits and the progression of MPN.

Single-cell transcriptome profiling of m6A regulator-mediated methylation modification patterns in elderly acute myeloid leukemia patients

Millions of people worldwide die of acute myeloid leukaemia (AML) each year. Although N6-methyladenosine (m6A) modification has been reported to regulate the pathogenicity of AML, the mechanisms by which m6A induces dysfunctional hematopoietic differentiation in elderly AML patients remain elusive. This study elucidates the mechanisms of the m6A landscape and the specific roles of m6A regulators in hematopoietic cells of elderly AML patients. Notably, fat mass and obesity-associated protein (FTO) was found to be upregulated in hematopoietic stem cells (HSCs), myeloid cells, and T-cells, where it inhibits their differentiation via the WNT signaling pathway. Additionally, elevated YT521-B homology domain family proteins 2 (YTHDF2) expression in erythrocytes was observed to negatively regulate differentiation through oxidative phosphorylation, resulting in leukocyte activation. Moreover, IGF2BP2 was significantly upregulated in myeloid cells, contributing to an aberrant chromosomal region and disrupted oxidative phosphorylation. m6A regulators were shown to induce abnormal cell-cell communication within hematopoietic cells, mediating ligand-receptor interactions across various cell types through the HMGB1-mediated pathway, thereby promoting AML progression. External validation was conducted using an independent single-cell RNA sequencing (scRNA-Seq) dataset. The THP-1 and MV411 cell lines were utilized to corroborate the m6A regulator profile; in vitro experiments involving short hairpin RNA (shRNA) targeting FTO demonstrated inhibition of cell proliferation, migration, and oxidative phosphorylation, alongside induction of cell cycle arrest and apoptosis. In summary, these findings suggest that the upregulation of m6A regulators in HSCs, erythrocytes, myeloid cells, and T-cells may contribute to the malignant differentiation observed in AML patients. This research provides novel insights into the pathogenesis of AML in elderly patients and identifies potential therapeutic targets.

PX-478 induces apoptosis in acute myeloid leukemia under hypoxia by inhibiting the PI3K/AKT/mTOR pathway through downregulation of GBE1

Acute myeloid leukemia (AML) is a highly heterogeneous hematologic malignancy characterized by limited therapeutic options and a pronounced tendency for relapse. PX-478, a novel inhibitor of hypoxia-inducible factor 1-alpha (HIF-1α), has demonstrated antitumor activity across various cancer models, but its specific role in AML remains unexplored. This study aimed to explore the potential target and mechanism of PX-478-induced AML cell apoptosis. First, PX-478 induced AML cell apoptosis in vitro under hypoxia via modulation of the Bcl-2 family and activation of the mitochondria-mediated caspase cascade, exhibiting a concentration-dependent effect. Additionally, in vivo administration of PX-478 led to notable inhibition of subcutaneous AML xenograft growth in mice, coupled with increased tumor cell apoptosis. RNA sequencing and cellular studies revealed downregulation of the PI3K/AKT/mTOR signaling pathway in PX-478-treated cells. Consistently, cellular studies also implicated PI3K/AKT/mTOR pathway in PX-478-induced AML cell apoptosis. Furthermore, by screening for RNA sequencing differential genes and subsequent experimental verification, Glycogen branching enzyme 1 (GBE1) may be involved in PX-478-induced apoptosis in AML cells. We found that inhibiting GBE1 expression in AML cells (siGBE1) led to downregulation of the PI3K/AKT/mTOR pathway and induced apoptosis. In experiments using AML cells with reduced GBE1 expression (shGBE1), PX-478 treatment did not further downregulate the pathway or enhance apoptosis. Re-expression of GBE1 in shGBE1 cells alleviated apoptosis and reduced PX-478- induced apoptosis and pathway downregulation. In conclusion, our findings provide convincing evidence that PX-478 induces apoptosis by inhibiting the PI3K/AKT/mTOR pathway through downregulation of GBE1 in AML cells.

Downregulating LKB1 in bone marrow mesenchymal stem cells could inhibit CD4+ T cell proliferation via the PD-1/PD-L1 signaling pathway

BACKGROUND

Our previous research has shown that LKB1 in amniotic mesenchymal stem cells (MSCs) serves as a vital regulator of regulatory T cell differentiation and T cell proliferation, which may have a similar role in bone marrow MSCs (BMMSCs). Therefore, we investigated the role of LKB1 in BMMSCs for regulating CD4+ T cell proliferation in the bone micro-environment of AML.

METHODS

RT-PCR was used to assessed LKB1 expression in BMMSCs derived from AML patients and healthy controls. Subsequently, LKB1 was knocked down in the BMMSCs line HS-5 (HS-5-LKB1KD). Co-cultures in vitro were established to analyze the effect of HS-5-LKB1KD on CD4+ T cell. Flow cytometry was employed to measure PD-L1 and CD4+ T cell proliferation levels. Western blot was utilized to detect related proteins.

RESULTS

The expression of LKB1 in BMMSCs derived from AML patients was decreased. Knockdown of LKB1 in HS-5 resulted in upregulation of PD-L1 expression. Co-culture of peripheral blood CD4+ T cell with HS-5-LKB1KD exhibited reduced CD4+ T cell proliferation compared to co-culture with HS-5-LKB1con. Furthermore, blocking PD-L1 in the co-culture conditions could restore the reduced CD4+ T cell proliferation. Additionally, it was found that upregulation of the Wnt signaling pathway-related proteins following LKB1 knockdown in HS-5, indicating that downregulating LKB1 could promote PD-L1 expression through activation of the Wnt signaling pathway.

CONCLUSIONS

The decreased expression of LKB1 in BMMSCs may activate the Wnt signaling pathway, leading to increased PD-L1 expression. This inhibited CD4+ T cell proliferation, which might lead to impaired anti-tumor immunity in AML patients and promote AML progression.

Acute Myeloid Leukemia in Older Patients: From New Biological Insights to Targeted Therapies

Acute myeloid leukemia (AML) is a heterogeneous blood-related neoplasm that predominantly afflicts older adults with a poor prognosis due to their physical condition and the presence of medical accompanying comorbidities, adverse biological disease features, and suitability for induction intensive chemotherapy and allogenic stem cells transplantation. Recent research into the molecular and biological factors contributing to disease development and progression has led to significant advancements in treatment approaches for older patients with AML. This review article discusses the latest biological and therapeutic developments that are transforming the management of AML in older adults.

A Dual-Function LipoAraN-E5 Coloaded with N4-Myristyloxycarbonyl-1-β-d-arabinofuranosylcytosine (AraN) and a CXCR4 Antagonistic Peptide (E5) for Blocking the Dissemination of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a hematological malignancy with a high recurrence rate. The interaction of chemokine receptor 4/chemokine ligand 12 (CXCR4/CXCL12) mediates homing and adhesion of AML cells in bone marrow, leading to minimal residual disease in patients, which brings a hidden danger for future AML recurrence. Ara-C is a nonselective chemotherapeutic agent against AML. Due to its short half-life and severe side effects, a lipid-like Ara-C derivative (AraN) was synthesized and a dual-function LipoAraN-E5 (135 nm, encapsulation efficiency 99%) was developed, which coloaded AraN and E5, a peptide of the CXCR4 antagonist. LipoAraN-E5 effectively improved the uptake, enhanced the inhibition of leukemia cell proliferation, migration, and adhesion to stromal cells in bone marrow, and mobilized the leukemia cells from bone marrow to peripheral blood via interfering with the CXCR4/CXCL12 axis. LipoAraN-E5 prolonged the plasma half-life of AraN (8.31 vs 0.56 h) and was highly enriched in peripheral blood (3.67 vs 0.05 μmol/g at 8 h) and bone marrow (379 vs 148 μmol/g at 24 h). LipoAraN-E5 effectively prevented the infiltration of leukemia cells in peripheral blood, bone marrow, spleen, and liver, prolonged the mice survival, and showed outstanding antineoplastic efficacy with negligible toxicity, which were attributed to the ingenious design of AraN, the use of a liposomal delivery carrier, and the introduction of E5. Our work revealed that LipoAraN-E5 may be a promising nanocandidate against AML.

Focal adhesion kinase as a new player in the biology of onco-hematological diseases: the starting evidence

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase mainly found in the focal adhesion regions of the plasma membrane and it has a crucial role in migration and the remodeling of cellular morphology. FAK is also linked to several aspects of cancer biology, from cytokine production to angiogenesis, drug resistance, invasion, and metastasis, as well as epithelial-to-mesenchymal transition. The gene locus of FAK is frequently amplified in several human tumors, thus causing FAK overexpression in several cancers. Furthermore, FAK can influence extracellular matrix production and exosome secretion through cancer-associated fibroblasts, thus it has an important role in tumor microenvironment regulation. Although the role of FAK in solid tumors is well known, its importance in onco-hematological diseases remains poorly explored. This review collects studies related to FAK significance in onco-hematological diseases and their microenvironments. Overall, the importance of FAK in blood tumors is increasingly evident, but further research is required to confirm it as a new therapeutic target in hematological contexts.

Therapeutic applications of melatonin in disorders related to the gastrointestinal tract and control of appetite

Most animals have large amounts of the special substance melatonin, which is controlled by the light/dark cycle in the suprachiasmatic nucleus. According to what is now understood, the gastrointestinal tract (GIT) and other areas of the body are sites of melatonin production. According to recent studies, the GIT and adjacent organs depend critically on a massive amount of melatonin. Not unexpectedly, melatonin's many biological properties, such as its antioxidant, anti-inflammatory, pro-apoptotic, anti-proliferative, anti-metastasis, and antiangiogenic properties, have drawn the attention of researchers more and more. Because melatonin is an antioxidant, it produces a lot of secretions in the GIT's mucus and saliva, which shields cells from damage and promotes the development of certain GIT-related disorders. Melatonin's ability to alter cellular behavior in the GIT and other associated organs, such as the liver and pancreas, is another way that it functions. This behavior alters the secretory and metabolic activities of these cells. In this review, we attempted to shed fresh light on the many roles that melatonin plays in the various regions of the gastrointestinal tract by focusing on its activities for the first time.